Behavioral Tolerance to Anticholinergic Agents
Final rept. 15 Jul 1983-15 Feb 1986
FLORIDA UNIV GAINESVILLE DEPT OF PSYCHOLOGY
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Squirrel monkeys were studied under four procedures in which their operant responses were maintained by either positive reinforcement food presentation or negative reinforcement avoidance of brief electric shocks. Each procedure was designed to allow within subject determination of drug effects. Another design feature was that reductions in responding resulted in different degrees of reduction of reinforcement frequency. Administered acutely, atropine reduced frequency of responding in a dose-related fashion, with responding maintained by positive reinforcement being much more sensitive to this action of the drug. Otherwise, there was little evidence that the type of reinforcement schedule influenced the action of the drug. Combining injections of atropine with injections of physostigmine yielded some evidence that atropine could antagonize the effects of physostigmine. Repeated administration of atropine after sessions did not result in consistent effects across subjects or across procedures. In some cases tolerance was observed, but in others it was not. Repeated post-session injections also did not result in consistent modification of the way that atropine interacted with physostigmine. Repeated pre-session injection of atropine also did not result in consistent effects across procedures or subjects, with effects ranging from tolerance to sensitization. The data collected indicate that, in squirrel monkeys, atropines behavioral effects tend to be highly idiosyncratic and difficult to predict.
- Anatomy and Physiology